Bears Do It

There may be only two thousand pandas in the world, of which a sixth are in captivity.Illustration by Martin Ansin

A female giant panda unambiguously signals her approaching receptivity to mating. She wanders over a wide territory and scent-marks stones, the ground, and other surfaces with a waxy, hormone-rich secretion from a gland under her tail. She walks through water, to spread her scent farther. Her main vocalization changes from a throaty whinny to a high-pitched chirp, which one zookeeper translated for me as “I’m here! I’m here! My time is coming!” She masturbates, and when she encounters an adult male at the critical moment she lumbers toward him, rear end first, and lifts her tail.

Still, things don’t always work out. David Wildt, the head of the Center for Species Survival at the National Zoo, in Washington, D.C., told me, “Some pandas know how to have sex, and some don’t.” The pair at the National Zoo—Tian Tian (male) and Mei Xiang (female)—don’t. They have been together at the zoo since 2000, but until last week they had produced just two cubs, both by artificial insemination, and one of these had died. At the end of last week, Mei Xiang gave birth for a third time, live on one of the zoo’s panda Webcams.

The latest arrival is also the product of artificial insemination. As Wildt described it to me, Tian Tian and Mei Xiang are simply “reproductively incompetent.” A key difficulty is that Mei Xiang places herself in what he called “pancake position”—flat on her stomach, legs outstretched—and Tian Tian isn’t assertive enough to lift her off the ground. Rather than mounting from behind or pulling her toward his lap, he steps onto her back and stands there like a man who has just opened a large box from Ikea and has no idea what to do next.

Female pandas are receptive only once a year, and sometimes are fertile for less than a day—an unusually narrow breeding window. As spring approaches, scientists at the National Zoo monitor Mei Xiang’s behavior and hormone levels, and a Chinese consultant prepares to fly to Washington on short notice, to assist. In China and elsewhere, panda handlers have encouraged unenthusiastic pairs by showing them “panda porn”—footage of other pairs having sex—and giving the males Viagra. Some handlers have claimed success with the videos, but pandas in the wild are solitary creatures, with limited opportunities to observe the behavior of other adults, and many scientists doubt that they engage in social learning.

The National Zoo’s approach has been more mechanistic. Last year, at the suggestion of the Chinese consultant, carpenters built a low wooden platform in the enclosure that had been Mei Xiang’s preferred mating location. “We were thinking that if she would pancake at a higher level Tian Tian might be able to hit the target,” Brandie Smith, the zoo’s panda curator, told me. It didn’t work. This year, two zookeepers placed a plastic cylinder, about a foot in diameter, across the threshold of the enclosure. As Mei Xiang led Tian Tian inside, she fell over the cylinder, and her rump rose into the air—exactly as the zookeepers had hoped. But then Tian Tian lifted her off the cylinder, placed her on the ground, and stepped onto her back.

The reproductive travails of giant pandas are ecologically significant, because the species today may consist of as few as two thousand animals, of which about a sixth are in captivity. (The rest are in wildlife reserves in a mountainous part of central China.) Captive breeding is a way of buying time while the Chinese sort out their feelings about a number of environmental issues, including habitat destruction. Most of the captive animals live in two large research centers, in Wolong and Shandong, but roughly three dozen are in zoos in other countries, and their mating failures and successes have inspired intense public interest. During breeding season in Washington, volunteer Behavior Watchers, fortified by caffeine, sit through the night in a glass-fronted booth, studying video monitors and taking notes on clipboards at four-minute intervals. They fill out “pee maps,” to show keepers where to find urine samples, for hormone analysis. Many more people watch unofficially, from home, by way of the zoo’s Webcams, and, occasionally, offer theories of their own. “One of the things we often hear is that Tian Tian and Mei Xiang don’t mate because they think they’re brother and sister,” Smith told me. “But that’s definitely not the case. We can see very clearly that they know they’re supposed to be doing something that is not brotherly or sisterly.” And yet.

Among the first Americans to see a giant panda were the two eldest sons of Teddy Roosevelt, Theodore, Jr., and Kermit, who encountered one on a scientific expedition to China in 1928. Not surprisingly, given the period and their parentage, they shot it, along with some eight thousand other creatures. (It’s now stuffed, in a diorama at the Field Museum, in Chicago.) In 1936, Ruth Harkness, a recently widowed American socialite, trekked fifteen hundred miles across China and returned with a nine-week-old male, which she named Su-Lin. (She thought he was a girl.) She fed Su-Lin baby formula during the voyage home, and sold him to the Brookfield Zoo, in suburban Chicago. Su-Lin attracted fifty-three thousand visitors during his first day on display. Shirley Temple and Eleanor Roosevelt came to see him, and Time named him Animal of the Year. He died, in 1938, of a throat infection, contracted after swallowing an oak twig, but by then the zoo had acquired a second panda (also from Harkness), and it soon acquired a third. Su-Lin was stuffed and given his own diorama at the Field Museum.

The modern American panda era began in 1972, when China gave the United States a wild-caught pair, Ling-Ling and Hsing-Hsing, to commemorate Richard Nixon’s historic visit. (The United States reciprocated with musk oxen.) They were housed at the National Zoo and eventually produced five cubs, although none lived longer than a few days. Ling-Ling died, of heart disease, in 1992, and Hsing-Hsing was euthanized in 1999. It has been estimated that seventy-five million visitors saw at least one of them. The zoo acquired its current pair a little over a year after Hsing-Hsing’s death.

Long before then, China had stopped giving pandas away. Mei Xiang and Tian Tian, like the forty or so other pandas in non-Chinese zoos around the world, are, in effect, rentals, since China retains ownership and can claim any offspring. (Tai Shan, the surviving adult cub of Mei Xiang and Tian Tian, was shipped to a breeding center in Sichuan in 2010, when he was four and a half years old.) The National Zoo initially paid China a million dollars a year for its pair; the current agreement is for half that amount. Three other American zoos—in San Diego, Memphis, and Atlanta—also have pandas, as do zoos in Australia, Austria, Canada, France, Japan, Mexico, Singapore, Spain, Taiwan, Thailand, and the United Kingdom.

For China, pandas rapidly became a potent global brand. By the nineteen-nineties, though, captive animals there were suffering a variety of serious ailments, including a high level of cub mortality, and few adults were reproducing, so that the Chinese were able to maintain their numbers only by trapping new specimens. In 1996, seeking help, they convened an international conference, in Chengdu, after which a team of scientists from China and the United States undertook a three-year biomedical survey of more than sixty pandas in China. Some of the main findings concerned diet. Giant pandas are classified taxonomically as carnivores—and they have the claws to back that up—but in the wild they live almost entirely on a small selection of the thousand-odd species of bamboo. They favor different types and different plant parts at different times of the year, and because bamboo is low in nutrients they consume huge quantities—as much as fifty pounds per animal per day. Yet the Chinese had been unable to acquire a steady supply, and had been feeding their animals milk, eggs, and a high-protein, low-fibre paste they called “panda bread.” They had also been careless about hygiene and record-keeping, and hadn’t been vaccinating for canine distemper virus, which makes pandas sick, too. The study led to many changes, as well as to an increased appreciation, among the participating scientists, for international coöperation. The pandas rapidly became healthier, and, among other things, began having more sex.

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When I visited the National Zoo’s pandas, this spring, Mei Xiang had recently been artificially inseminated, following the pair’s latest unsuccessful attempt at natural breeding. To obtain the semen, veterinarians had inserted a low-voltage probe into Tian Tian’s rectum, positioned it near his prostate, and pulsed the current. Suzan Murray, the chief veterinary medical officer, gave me a tour of the facility in which the procedure had taken place. In one operating room, I saw an examination table mounted on a hydraulic lift. Murray said that the zoo’s vets had used it for a zebra whose intestine had become twisted—an operation that involved opening the animal’s abdomen and untangling the intestine as though it were a garden hose. On the far wall was a calendar, drawn on a whiteboard with colored markers: I saw that an oryx and a macaque were going to have vasectomies the following week, and that Tian Tian had been scheduled for another electro-ejaculation. The new ejaculate would be frozen, and stored in liquid nitrogen in one of several dozen freezers the zoo uses for such purposes. Freezing semen was first done in the cattle industry, in the nineteen-fifties, and the technique was later applied to other animals, including humans. The zoo’s collection includes samples from many endangered species, but not all. Scientists still don’t know how to properly freeze elephant semen.

“I want to spill the beans, but I’m waiting till I have access to classified or sensitive beans.”

A little later, Brandie Smith, the panda curator, took me into a non-public area in back of the panda enclosure. We stood behind a painted yellow line, which marked the distance an adult panda can reach with a paw, and watched while Tian Tian came up to the fence to receive various treats. Pandas resemble enormous plush toys—a key element of their appeal to humans—but their eyes are broadly expressive, in the way that dogs’ eyes are. Pandas also have a prominent bone in their forepaws which functions almost like a human thumb. As a consequence, they are able to hold things almost as we do, making them seem less like real bears and more like Disney animations. Tian Tian, as he moved from treat to treat along the edge of his enclosure, had a heavy ursine gait, but when he stood and gripped the fence he became a storybook character.

I met Mei Xiang a little later, in a different area. She rapidly made her way down a tunnel-like cage, called a training chute, and when she got to the end—where I was standing with Smith and several keepers, behind another yellow line—she sat, extended her left foreleg through a small opening, onto a metal tray, and, using her opposable pseudo-thumb, gripped a bar at the end of the tray. The tray is used for drawing blood, and gripping the bar prevents a panda from accidentally clawing a human. This time, the veterinarians didn’t need blood, but Marty Dearie, one of the keepers, used a finger to prod the inside of her elbow anyway, to keep her in practice, and then rewarded her with a squirt of something sweet from a squeeze bottle.

At one time, blood draws and other routine veterinary procedures could be done only under general anesthesia, but Mei Xiang and Tian Tian have both been trained to open their mouth for an oral examination, offer a shoulder for an injection, and hold their forepaws above their head, airport-security style, for a chest X-ray. Handling zoo animals this way began in the nineteen-eighties, using “operant conditioning” techniques borrowed from performing-animal handlers. Since then, polar bears have been taught to participate in hearing studies; elephants have learned to extend a foot through the bars of their enclosure and keep it elevated for a podiatric examination; great apes that need to be knocked out for a complex medical procedure have been taught to allow a keeper to inject them with an anesthetic and then, if the initial dose proves insufficient, to come back for a second. A properly trained lion, responding to hand signals and spoken commands, will hold its mouth open for a dental exam and lean against its cage to receive a vaccination.

“With great apes,” Dearie said, “you just show them what you want and they’re, like, Oh, O.K., I’ll figure that out—because their minds work more like ours. Pandas think differently.” Trainers teach pandas new behaviors not by demonstrating them but by using treats to reward movements that are serendipitously similar to the ones they’re looking for. Then they gradually incorporate additional elements, as though they were assembling a puzzle. Nothing is done coercively. Mei Xiang had entered the training chute voluntarily, and she was free to leave.

Elementary-school teachers, among others, will not be surprised to learn that females in most species learn faster and pay attention longer than males do, and that very young animals sometimes pick up behaviors that are being taught to a parent, just from watching. Mei Xiang won’t urinate on command, as the female panda in San Diego will, but she has learned a number of complex movements, including a sideways shuffle that her keepers call a “scooch,” which they use to reposition her. She will also squat for a pelvic examination, and lie on her back so that her abdomen can be shaved for an ultrasound scan of her uterus, and she will keep still for the scan itself. Dearie demonstrated by holding his own arms above his head and making a swooning motion to one side. Mei Xiang did as he had done, then rolled over on her back.

“She loves, loves, loves ultrasound,” Murray said. “I can’t smell the gel, but for some reason she likes the taste.” The zoo has a portable ultrasound machine, which was paid for by a donor and is used only on pandas. Murray continued, “As soon as we’re done, she rubs her stomach and licks the gel and does this cute panda dance.” Tian Tian is now being trained for cardiac ultrasound, because heart disease is an issue in older pandas, at least in captivity. Hanging from a hook on a wall not far from the training chute was a child’s lacrosse stick, which the keepers had been using to accustom him to having a probe pressed against his chest.

Some zookeepers were initially skeptical about training animals in this way, but the benefits have gone beyond reducing the need for anesthesia. Animals enjoy challenging activities, it turns out, and Murray told me that the sessions have also strengthened the pandas’ relationship with their handlers. The bonding works in both directions. When Murray was pregnant with the first of her three children, she had an ultrasound exam, and as she studied the image on the monitor she told the doctor, “That’s amazing! You can see all four feet!” The doctor reminded her that, in human medicine, “two of them are called hands.”

In 1996, the San Diego Zoo received Shi Shi, a male, and Bai Yun, a female, through the Chinese loan program. The two bears did not hit it off. “Bai Yun was definitely soliciting him, but he would have nothing to do with her,” Kathy Hawk, who has worked at the zoo since 1986, told me. “And, since Shi Shi wasn’t coöperating, Bai Yun would literally beat him up.” To prevent injury, the keepers resorted to artificial insemination, which eventually produced a cub, in 1999. A few years later, the Chinese took back Shi Shi and sent another male, Gao Gao, as a replacement. Gao Gao arrived shortly before the beginning of breeding season, but in the wild he had been injured and severely dehydrated, so the zoo’s staff assumed that he would need at least a year to recuperate. They were wrong. “We all just went, Whoa!” Hawk said. “We were floored. And since then we’ve never had to use artificial insemination.”

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Gao Gao has no need for sex aids fashioned by zoo carpenters. Suzanne Hall, another researcher at the San Diego zoo, told me, “In the spring, he starts pacing around, because in the wild, at that time of year, males would be looking for females.” Gao Gao and Bai Yun live in separate but adjacent enclosures, which are connected by a gate that’s almost always kept closed. Hall went on, “He will spend a lot of time at that gate, calling to her. When she’s not ready to breed, she will ignore him or charge toward the gate, to let him know that now is not the time, and it’s part of his really great mating behavior that he doesn’t push it: he knows when he’s invited and when he’s not. But, when her hormones and her behavior indicate that the time has come, he gets really frantic at the gate—like, I need access to this female right now—so we open it, and they couple, and then they separate, and we close the gate again.” This routine is repeated several times over two or three days. “Usually, it’s Gao Gao who lets us know it’s over,” Hall continued. “He knows where the on and off switches are, and when she’s done he’s done. He’s just not interested anymore.”

Scientists are dispassionate observers of the natural world, of course, but it’s hard to believe that researchers at the National Zoo don’t take the breeding success of Gao Gao and Bai Yun personally, as I do. (Why do the East Coast pandas have to be the ones with the copulation problems?) Brandie Smith told me that men observing the fumblings of Tian Tian and Mei Xiang tend to wish they could intervene with a joystick or a videogame controller, while “the women are, like, ‘Get up! Get up!’ ” Staff members at the National Zoo don’t know whether their pandas’ difficulties are solely the result of technical incompetence or are exacerbated by a fundamental incompatibility. If the bears were wild, they would likely have mating opportunities with other partners, and would thus be able either to learn from experience or to encounter more skillful hookups. In Washington, though, they’re stuck with each other. Meanwhile, the San Diego pair have had five cubs together, all of them the result of natural breeding.

Mei Xiang has frequently raised the hopes of her keepers, but pandas that seem pregnant often aren’t. Non-pregnant females routinely go through a pseudo-pregnancy, which is indistinguishable from the real thing both behaviorally and hormonally. In addition, panda embryos don’t immediately attach to the uterine wall—a delay known as embryonic diapause, which occurs in about a hundred mammal species and may enable pregnant females to postpone the energy demands of gestation and birth when conditions are unfavorable. Because of that lag, a normal panda pregnancy can last anywhere from three months to five. In addition, there is no certain way to confirm that a pregnancy is real until just before its end. (A technician at the National Zoo once tried a drugstore pregnancy test on Mei Xiang. It didn’t work, but the idea wasn’t outlandish: an ovulation test developed for dogs also works on elephants.) Two weeks before birth, Suzan Murray told me, a panda fetus appears on an ultrasound as just “a dark circle with a little white dot, less than a centimetre in diameter.” The San Diego Zoo made the first-ever ultrasound image of a fetal panda in 1999, three days before it was born; the National Zoo has never been able to make one.

At birth, pandas are blind, pink, helpless, and approximately hamster-size, and they weigh about the same as a stick of butter. “They can’t thermo-regulate,” Kathy Hawk told me. “It’s important for the mother to keep that cub warm, by holding it to her sternum, so a lot of times in the first few weeks you hear a new cub more than you see it.” Cubs become recognizable as pandas after a few weeks, and attempt to crawl after about two and a half months. When I was in San Diego, I got a close look at Xiao Liwu, who was eleven months old and near the peak of juvenile adorability. He had descended from his favorite daytime resting place, high in a tree, in order to eat something sweet that a keeper was spooning from a yogurt container. Bai Yun, who wanted the treat for herself, tried to move him out of the way, but he pushed her paw aside with his head and went back to licking the spoon.

Last September, Mei Xiang surprised everyone by giving birth. National Zoo staff members and patrons were ecstatic. But a few days later she began making honking distress calls, and the zoo’s keepers and veterinarians realized that something was terribly wrong. After a tense deliberation, a keeper entered the enclosure and removed her cub, which wasn’t breathing. The vets tried C.P.R. and artificial respiration, but they couldn’t revive it. Later examination suggested that the birth might have been premature. Zoo officials decided to keep the panda exhibit closed, but many fans arrived, anyway, to pay their respects.

You might think that the way to solve the captive-panda breeding problem would be to turn the whole thing over to pairs like Gao Gao and Bai Yun, but superfertile animals create problems of their own. Bai Yun is a daughter of Pan Pan, a wild-caught panda, who now lives in a facility in Zunyi. He was such a capable breeder that the Chinese relied on him heavily during the years when their sole goal was to increase their panda supply, and in his youth he fathered more than thirty cubs. According to Jonathan Ballou, a geneticist at the Smithsonian Conservation Biology Institute, the Chinese bred Pan Pan so often that around sixteen per cent of the genes in the captive population were his. “So our first job was to persuade them to start using other males,” he said. “It took them a few years, but Pan Pan is no longer a breeder.” (Overrepresentation in their gene pools was the reason that vasectomies had been scheduled for that oryx and that macaque.)

Giant pandas, like many other endangered animals with captive populations, have a species manager and an official studbook, which is updated regularly. (A growing number of technically wild populations, like rhinoceroses, have managers and studbooks, too, because their numbers are so small and their territory is so confined that all surviving members can be individually identified.) Ballou showed me a recent panda studbook, a telephone-directory-size paperbound volume. “In studbooks, we keep track of the mom and the dad, the date of birth, the date of death, and where the animals have moved around,” he said, as he thumbed through the pages. “And all that allows us to analyze the pedigree and make breeding recommendations.” In the late nineties, Ballou devised a simple measure of genetic rarity, called “mean kinship,” for determining which animals in any captive population should be favored for breeding; it’s based on the number of shared ancestors and the closeness of those relationships, and it’s relatively easy to calculate. Each year, the species manager sets mating goals and ranks the desirability of particular pairings, based largely on Ballou’s metric. There are many constraints, including geographical ones, but following the guidelines reduces the gradual loss of diversity over generations—an inevitable occurrence in small populations.

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I asked Ballou whether an effort was made to pick mates with especially desirable characteristics. “We try to avoid that,” he said. “One trait you might think to select for would be fecundity. But it’s probably not true that pandas that are good breeders in captivity would also be good in the wild, and we don’t want these guys to become domesticated, or adapt to the captive environment.” In addition, a trait that seemed valuable to scientists today might look different fifty years from now. “Basically, we’re trying to freeze evolution in the captive population,” he said. “Eventually, when pandas are available for reintroduction, their genes will resemble the genes of the founding population as closely as possible.”

Pandas born in zoos or breeding centers can’t simply be released, even in a reserve, because in captivity they learn to be unafraid of their principal predators: us. Wild pandas avoid human contact to such an extent that a researcher could spend years studying them without ever seeing one in its natural habitat, but once they get used to people they become vulnerable to hunters, poachers, and civilization in general. The Chinese made a few early attempts at releasing pandas born in breeding centers, but those animals either died quickly or returned. In recent years, a researcher at Wolong has tried a more daring approach, by raising pandas that have never seen humans. To accomplish that, handlers never enter a cub’s field of vision unless they are wearing a full panda suit, which makes them look like the mascot of a Chinese athletic team. (If a newborn needs to be weighed, a keeper will put on a panda suit before placing it on a portable scale.) When the cub is older, it’s released in stages, through a succession of increasingly spacious enclosures, the last of which it enters by way of an opening too small for its mother. Gradually, the cub becomes accustomed to independence, and eventually it moves off to establish its own territory, as wild-born pandas do.

Scientists, veterinarians, and zookeepers now know vastly more about the reproductive health of giant pandas than they did even a decade ago, but not everyone believes that the investment of time and money has been worthwhile. The physical characteristics that endear pandas to humans can also make them seem like a wildlife novelty act. Pandas are among a number of endangered animals that are sometimes classified, not flatteringly, as “charismatic megafauna,” which attract money and attention out of proportion to their numbers. The British naturalist Christopher Packham once offered to “eat the last panda” if doing so would free up funding for less photogenic species with better chances of survival outside zoos. Brandie Smith told me that some people, including some scientists, have argued that captive pandas’ mating difficulties are evidence that the species is “meant to go extinct.” She is scornful. “Giant pandas evolved millions of years ago,” she said. “They’re bears that eat grass. They’re perfectly, beautifully adapted to exploit an abundant resource. And then human beings come along, mow down their habitat, and decide, Well, they were meant to disappear. That drives me crazy.”

William J. McShea, a colleague of Smith’s, told me that saving pandas can be good for other animals, too. McShea’s primary research focus is ecology and conservation of wildlife, and he said that pandas are an important “umbrella” species. “Most of China’s panda reserves have a big elevation gradient,” he said. “You go from lowlands to highlands, and it’s all very steep, because if it were flat and could be farmed there would be a thousand people living on it.” The main reason wild pandas still exist is that they do well in such environments. And sanctuaries created for them fortuitously help animals that thrive in the same terrain but which the Chinese have devoted less attention to protecting, including takins and less cuddly-looking kinds of bears. “Black bears have a lot of territorial overlap with giant pandas in this region,” McShea said. “If you create a park for pandas, you’re also preserving black bears, which in China are running for their lives.” (Black bears are the usual source of bear paws, a delicacy in Chinese restaurants, and bear bile, a popular pharmaceutical ingredient, which is harvested by confining bears in very small cages, sometimes for decades, and drawing bile through a tube inserted permanently in their gall bladder.)

“The Chinese are very utilitarian,” McShea continued. “We did a lot of black-bear surveys, in which we interviewed villagers, townspeople, teachers—and if they used gall bladder they said they loved bears, and if they didn’t use it they saw no purpose for bears whatsoever. What we’ve learned is that, if you want to talk to them about conserving wildlife, you have two angles. The first is national pride: these animals are yours alone, they exist only in China, it’s up to you to save them, and if your national government can do that you will be world-famous. The second is utilitarian: these animals are useful, they help this ecosystem function, they clean your water, they grow your trees, and you need them to have an environment you can live in.”

One of McShea’s main efforts in recent years has been encouraging the Chinese to create larger, less isolated reserves, by setting aside bigger tracts and using new acquisitions to enlarge and connect existing ones. That effort has often been frustrating, but he has noticed what he believes might be signs of a change in thinking. “The universities now have birding clubs,” he said. “That was unheard-of twenty years ago. And it’s happening just the way it happened here: you’ve got your bird list, and you want to get the most birds, so now you see the value of a park that would shelter twenty species. It’s a competitive sport, but you’ve got to start somewhere—so, all right, let’s have a competitive sport. The thing that doesn’t work with the Chinese is to say you need to protect these animals because you love them, or because they’re so cute.”

Fifteen years ago, the Chinese needed international help to address their panda-breeding difficulties; today, much of the scientific research on pandas is Chinese. The original goal was to increase the captive population from a hundred and twenty to three hundred—a level at which, Jonathan Ballou told me, it’s possible to maintain ninety per cent of current genetic diversity for a hundred years. Success has exceeded expectations, and the captive population passed three hundred last year, far ahead of schedule. Instead of declaring victory, Ballou told me, “the Chinese have decided to raise the goal to ninety per cent for two hundred years, which requires about five hundred animals.” That decision represents a major step in thinking about human impact on other living things, he said. What no one understands, yet, is how to turn that success, and others like it, into a solution to the larger problem, which is the long-term survival of all endangered species, including uncharismatic ones, as well as the preservation or restoration of the ecosystems that sustain them. The occasional miraculous-seeming panda birth notwithstanding, the signs aren’t encouraging.

Still, as Bill McShea said, you’ve got to start somewhere. When I visited the National Zoo, I spent an hour or so loitering in the panda building as herd after herd of human cubs passed through. On the long wall opposite the panda enclosure, a well-designed photographic display clearly explained the pancake problem and the preferred solution to it, among other topics of potential interest to young visitors. But no one was looking at the display. Tian Tian was napping on a big rock in the center of the enclosure, and almost all the children were watching him—and squealing, here and there, when he moved in his sleep, proving that he was real. ♦